Temperature-controlled containers are commonly used for shipping perishable cargo, such as fresh produce and other foods, which must be maintained during transit at a temperature within a specified temperature range to maintain freshness and minimize spoilage. Containers of this type are typically designed to accommodate transport by road on trailers, by sea on container ships, by rail on flat-bed train cars and even by air in cargo planes. Such versatile containers are commonly referred to as intermodal containers.
In conventional industry practice, temperature controlled containers are equipped with a refrigeration unit, commonly referred to as a reefer, that is secured to one wall of the container, typically the front wall of the container. The refrigeration unit includes a compressor, a compressor motor, and a condenser unit isolated from the cargo space, and an evaporator unit operatively associated with the cargo space defined within the container. The refrigeration unit is adapted to receive electrical power from an external source. During ship board transit, the refrigerant unit is typically connected to a ship board power supply, while in transit by road or rail, a diesel engine driven generator, commonly referred to a gen-set is temporarily attached to the container for generating electricity for powering the refrigeration unit.
Depending upon the product being shipped, it may be desirable to install an auxiliary system in operative association with the refrigeration unit to temporarily customize the container for the duration of a trip. At the end of the trip, the auxiliary system may be removed to de-customize the container. In situations where the auxiliary system requires electrical power, it is necessary to field wire the container pre-trip to provide an auxiliary power circuit for supplying electricity from the refrigeration unit's power supply and then to remove the auxiliary power circuit post-trip. To reduce the field labor and the time involved in pre-trip installation and post-trip removal of an auxiliary system and associated auxiliary power circuit, a need exists to provide a transport refrigeration system for a container having a built-in auxiliary power circuit for supplying electrical power to an optional installed auxiliary system in a safe manner.